RMO-TT series

RMO-TT series is perfect for measuring winding resistance of inductive objects such as power and distribution transformers or autotransformers.


Additionally, every transformer resistance meter from RMO-TT series can analyze:

  • tap changers,
  • generators,
  • electrical motors,
  • high-current busbar joints,
  • cable splices,
  • and welding joints.

Transformer demagnetization can also be performed with all RMO-TT instruments.

The series is consisted of 3 models, with maximal test current from 40 A (RMO40TT) to 100 A (RMO100TT). RMO100TT is the only portable transformer resistance meter in the market with 100 A DC output current. The three independent channels enable the testing of three windings in series. Consequently, a user can measure winding resistance in every tap position of an on-load tap changer without discharging between the tests. In addition to winding resistance measurement, a user can perform a detailed on-load tap changer analysis by analyzing recorded graphs (10 kHz sampling rate) and by measuring vibrations on an external tap changer tank.

All RMO-TT instruments have a built-in tap changer control unit. Because of this, it is possible to remotely control the on-load tap changer (OLTC) directly from the device. Also, a user can program DV-Win software to do everything automatically – running winding resistance tests and changing OLTC tap positions. The DV-Win software also enables control and observation of the test process, as well as saving and analyzing the results on a PC. It provides a test report, arranged in a selectable form as an Excel spreadsheet, PDF, Word, or ASCII format. Additionally, DV-Win measures and calculates the OLTC transition time, the ripple and the winding resistance for each tap changing operation. The software can also perform the calculations necessary for the “Heat Run” test.

All results can be exported in the report format.